Pivoting vent stops are in general well known devices that are designed to be mounted on sash rails of double hung windows or other slidable window arrangements in a position to allow a window sash to be opened to, but not beyond, a predetermined position. A typical pivoting vent stop includes a housing arranged to be mounted in a sash frame, a tumbler pivotally mounted in the housing and movable between retracted and extended positions, a spring for biasing the tumbler toward its extended position, and some form of retention means for retaining the tumbler in a retracted position. When the tumbler is retracted, a window sash may slide over the housing and thus be moved to fully open position. When the tumbler is in an extended position, however, it engages the sash after partial opening thereof and blocks further opening movement. When it is necessary or desirable to fully open the sash, the tumbler is pushed back into its housing and held in a retracted position until needed.
An early form of pivoting vent stop is reflected in the Szapucki et al U.S. Pat. No. 6,572,158, which incorporates a pivoted tumbler biased toward an extended position by a spring. In order to retain the tumbler in a retracted position, when desired, the tumbler can be pressed inward and then slid on a loose pivot connection until an end portion of the tumbler lies underneath a lip on the housing. The tumbler is released, when desired, by sliding the tumbler in an opposite direction to free the end portion and allow the tumbler to be pivoted outward by the biasing spring. A shortcoming of this type of device is the inconvenience of manipulating the tumbler for locking and unlocking it in or releasing it from a retracted position.
A different form of pivoting vent stop is represented by the Liang et al U.S. Pat. Nos. 7,600,796 and 7,637,544. In each of these devices, a tumbler is pivotally mounted in a housing and biased to a projected position by a spring. A separate, spring-biased latch mechanism is contained within the housing to engage the tumbler, when retracted, and retain it in a retracted position until the user desires to release it into an extended or locking position. A push-button type of release is provided for the latch mechanisms, such that the tumbler can be retracted by pressing on the projected end of the tumbler, and released by pressing on the push button release for the latching mechanism. A shortcoming of these designs is their relative complexity and corresponding higher cost, as well as a somewhat larger physical size to accommodate the presence of the release mechanism.
Yet another form of pivoting vent stop is represented by the Liang et al U.S. Pat. Nos. 7,530,611 and 8,235,430. Each of these devices utilizes a special spring element which is attached to a pivoted tumbler and has a horizontally extending portion that slides over a contoured bottom of the housing in which the tumbler is mounted. The combination of the sliding spring and the contoured housing bottom is intended to cause the tumbler to be self-retaining in retracted or extended positions without the need for special locking and/or releasing mechanisms. This arrangement, while having certain desirable functional features has the shortcoming of requiring extra parts and the assembly operations associated therewith, which adds extra cost to a highly cost-sensitive product.
There remains a need for a pivoted vent stop that is fully functional but which nevertheless requires an absolute minimum of parts, resulting in lower manufacturing and assembly costs.